"Didi is a great player, one of the top players I have played with at Liverpool," said Alonso.
"I played a lot of games with Didi in my first season and I could really see how he controlled games and how he instinctively knew what to do in certain situations.
"I really enjoyed playing with him - it was easy. He is a great player who gives great balance to a team.
"He tried to complement whoever he was playing alongside and do a good job for the team. He was also one of those experienced players who was good for the dressing room and who always performed on the pitch.
"He has been one of the key players for Manchester City this season. He has a lot of experience and we know all about him - but he knows a lot about us as well.
"We will have to keep an eye on him."